London: Older women who want to slim down could be doing more harm than good if they don't manage to stick to the diet, experts have warned.

According to a new study, over-50s who managed to lose weight before piling it back on again increased their risk of heart disease.

Researchers from Wake Forest University in North Carolina looked at risk-factors that contributed to type 2 diabetes and heart problems in post-menopausal women.

They found that although bad cholesterol, blood pressure, triglycerides, and blood sugar all improved with weight loss, they returned to pre-diet levels and in some cases, to even higher levels, if the pounds were put back on.

"In this group of women, weight loss and maintaining that loss offers the most health benefit, but therein lies the problem," a daily quoted study leader Daniel Deavers as saying.

For the study, the researchers studied 112 obese older women over 15 months. For the first five months the participants were encouraged to lose weight by eating more healthily and exercising. During this period they lost an average of 25lbs each.

A follow up a year later revealed two-thirds of the women had regained at least four pounds. On average the participants had regained 70 per cent of their lost weight, which actually left them worse-off.

"For women who had regained weight in the year after their weight loss, several risk factors were actually worse than before they lost the weight," study co-author Kristen Beavers said.

The study has been published online in the Journal of Gerontology: Medical Sciences.